Abstract:

Objective Hospital acquired pneumonia（HAP）is one of the most common nosocomial infec⁃ tions and often causes prolonged hospital stay and increased mortality. The elderly population is a high proportion of HAP，which needs more attention from clinicians. The purpose of this study is to analyze the clinical characteristics and risk factors of elderly HAP，in order to provide evidence for early clinical intervention and decision making，to improve prognosis and reduce mortality. Methods The patients with HAP diagnosed in our hospital from January 1，2014 to January 1，2018 were included，and their medical records were retrospectively analyzed. The patients were divided into a survival group and a death group，and their clinical characteristics and death ⁃ related risk factors were analyzed. Results Of 497 enrolled patients with HAP，50% ~ 60% had symptoms of fever，cough and purulent sputum，9.7% had dyspnea symptom and often accompanied by cerebrovascular disease and diabetes. The average blood urea nitrogen/albumin ratio was（0.224 ± 0.157）mmol/g，21.5% had multidrug⁃resistant bacterial infection，and 48.9% had a history of antibiotic use within 90 days before onset. The death toll was 76（15.3%）. According to COX regression analysis，purulent sputum，dyspnea，history of antibiotic use 90 days before onset， history of chemoradiotherapy，multidrug ⁃ resistant bacterial infection，and increased blood urea nitrogen/albumin levels were the risk factors for death of elderly patients with HAP. The area under the ROC curve of blood urea nitrogen/albumin level was 0.703. The survival time of HAP with high blood urea nitrogen/albumin ratio was signifi⁃ cantly lower than that of the control group. Conclusions Symptoms were atypical in the elderly patients with HAP，who had many complications，multiple drug⁃resistant bacteria infection and high mortality. Blood urea nitrogen/ albumin ratio is a simple and valuable risk factor for death，which deserves clinicians′ attention.

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